Partial oxidation or steam reforming method using petroleum or natural gas as raw material has been proposed as one of methods for producing hydrogen. However, these methods emit a huge quantity of carbon dioxide upon hydrogen synthesis.
UT-3 cycle and method disclosed in Japanese Patent Application Laid-open No. Hei 07-267601 using solar thermal power have been proposed as methods wherein no carbon dioxide is emitted. However, these methods require a large system upon using solar thermal power, and accordingly, require a large cost.
As another method, proposed is a method wherein methane as main component is decomposed into carbon and hydrogen using catalyst. For example, Japanese Patent No. 2767090 proposes that hydrocarbons such as methane is thermally decomposed in the presence of carbon material which has an outer surface larger than 1 m2/g. However, according to this proposed method, it is necessary to heat at an extremely high temperature of about 1,000° C. upon thermal decomposition, and accordingly, it is disadvantageous. Further, Japanese Patent No. 2838192 proposes catalyst for decomposing hydrocarbons such as methane comprising carbon material having nickel compound and at least one metal selected from alkali metal and alkaline earth metal carried thereon. However, according to this proposal, methane cannot be fully decomposed from standpoint of thermal dynamics, and further, since methane is supplied with a large amount of nitrogen gas and so on, the decomposing ratio of the methane in the supplied gas is low, and therefore it cannot be practically used.
Further, in case of fuel cells wherein hydrogen and air are used as raw materials, method for supplying hydrogen by way of steam reforming of methanol or gasoline is generally used and many inventions have been proposed. However, in either proposed methods, generation of carbon monoxide and that of carbon dioxide take place simultaneously, and especially, carbon monoxide requires a device for decreasing its concentration to a value lower than 10 ppm so as to avoid poisoning of electrodes of fuel cells, and accordingly, the cost is extremely high.
Contrary to this, in one of hydrogen supplying methods, hydrogen is supplied by means of a high pressure gas cylinder. However, high pressure cylinder is heavy and voluminous, and accordingly, it is difficult to load a lot of hydrogen on an automobile, and further, there is another problem such as possibility of explosion.
In place of high pressure gas cylinder, various use of hydrogen absorbing alloy have been proposed as means for safely storing and transporting hydrogen. However, there is a problem that hydrogen absorption in hydrogen absorbing alloy requires high hydrogen pressure, or that under the condition wherein hydrogen is absorbed in hydrogen absorbing alloy, it cannot be used in the air and steam atmosphere.
In view of the state of art, it is an object of the present invention to provide a method and apparatus for supplying hydrogen at low cost without emission of carbon monoxide or carbon dioxide and at the same time it can supply pure hydrogen which is free from carbon monoxide as apparatus for supplying hydrogen to fuel cells and so on, and the present invention also provides a portable cassette for supplying hydrogen.